1. Field of the Invention
The present invention relates to an emulation system for microcomputers.
2. Description of Related Art
At present, so-called emulation systems are indispensable to development of programs for different microcomputers. However, the conventional emulation system is constructed under the assumption that a target microcomputer to be emulated has an on-chip memory area of a fixed capacity, for example 256 bytes, and a memory area exceeding 256 bytes is provided as an external memory. Therefore, if a target microcomputer chip having an on-chip memory area of for example 512 bytes is emulated, a first half of the 512 bytes is accessed as an on-chip memory access, but a second half of the 512 bytes is accessed as an external memory access. In other words, the second half of the 512 bytes cannot be properly emulated as on-chip memory access.
With advanced integrated circuit technology, on the other hand, recent LSIs can access an on-chip memory in two cycles although they still require five cycles for access to an external memory (not the on-chip memory). If the above mentioned second half of the 512 bytes is accessed as an external memory access, the emulation cannot be executed by the emulation system under the same access time as in the case of the target microcomputer.